中南大学刘金龙， Small：Na2Ti3O7纳米阵列形貌对钠离子存储的影响
【Article Information】
To further explore the effect of Na2Ti3O7 nanoarray morphology on sodium ion storage
First Author: Chen Xiangxiong
Corresponding Author: LIU Jin-long*
Affiliation: Central South University
【Background】
In recent years, sodium-ion batteries (SIBs) have become the most promising alternative to lithium-ion batteries (LIBs) by taking advantage of the abundant sodium resources on the planet. Similar to LIBs, the development and application of SIBs also relies on finding suitable cathode and anode materials. In terms of host materials (e.g., negative electrodes), traditional graphite used for LIBs is not suitable for use as a negative electrode for SIBs because it cannot accommodate heavier and larger sodium ions (Na+), resulting in slow Na+ transport and unsatisfactory storage. Among the various candidate materials explored so far, titanium (Ti)-based materials have attracted extensive attention due to their advantages of good safety, good stability and low cost. Among them, sodium titanate (Na2Ti3O7)-based anode has a good prospect as a Na+ storage material for SIBs.
Nanostructure engineering has been shown to improve the performance of Na2Ti3O7 as an anode material, as the nano-sized Na2Ti3O7 material has the dual advantages of increasing the active site and reducing the Na+ diffusion path. However, the effect of Na2Ti3O7 nanoarray morphology on Na+ storage is unclear due to the usual use of binders and conductive additives in the preparation of Na2Ti3O7 anodes for SIBs. Therefore, self-supporting Na2Ti3O7 nanoarray electrodes prepared without adhesives or conductive additives provide an ideal platform for exploring morphological effects. Further understanding of the effect of Na2Ti3O7 nanoarray morphology on Na+ storage performance will promote the application of anodes based on Na2Ti3O7 nanosheets in the development of high-performance SIBs in the future, and lay a solid foundation for the rational design of high-performance anode materials in the future.
【Introduction】
近日，来自中南大学的刘金龙副教授课题组，在国际知名期刊Small上发表题为“Deeper Insights into the Morphology Effect of Na2Ti3O7 Nanoarrays on Sodium-Ion Storage”的研究文章。 文章报道了一种在Ti箔基底上成功制备自支撑Na2Ti3O7纳米片(NTO NSs)和Na2Ti3O7纳米管(NTO NTs)的水热合成方法，并对所制备电极的结构和电化学性能进行了详细的研究。 结果表明，与NTO NTs相比，NTO NSs在SIBs中的可逆容量、速率能力和长期耐用性方面具有更优越的性能。
【Main points of the text】
要点:Na2Ti3O7 She never asked me
The Ti foil was treated with different temperatures in the aqueous solution of sodium hydroxide by hydrothermal method, and then calcined to prepare nanoarrays with different morphologies. At the hydrothermal reaction temperatures of 180°C and 220°C, Na2Ti3O7 nanosheet arrays and nanotube arrays (NTO NSs and NTO NTs, respectively) were obtained, respectively.
图1 .(a) NTO NSs和NTO NTs的合成示意图;NTO NSs的SEM图像(b),TEM图像(c),HRTEM图像(d), HAADF-STEM图像(e) 以及相应的EDX元素映射图;NTO NTs的SEM图像(f),TEM图像(g),HRTEM图像(h), HAADF-STEM图像(i) 以及相应的EDX元素映射图。
要点二:NTO NTs和NTO NTs作一体化电极用于Na+存储的性能比较
Self-supporting NTO NSs and NTO NTs are used directly as the anode of sodium-ion batteries without the addition of binders and conductive additives. The results show that NTO NSs electrodes exhibit slightly higher specific capacity and better rate performance than NTO NTs, indicating that 2D nanosheets are more conducive to Na+ intercalation and deintercalation than 1D nanotubes. In addition, NTO NSs exhibit excellent durability in long-term cycling, which proves the importance of Na2Ti3O7 nanoarray topography for the stable operation of SIBs.
图2. (a) NTO NSs和NTO NTs的速率能力;(b) NTO NSs和 NTO NTs在第一百次循环时的恒流放电/充电曲线;(c)5C时NTO NSs和NTO NTs的循环稳定性和(d)相应的库仑效率。
Point 3: Identification of the influence of topography on Na+ storage performance
Based on electrochemical impedance spectroscopy, SEM observation, and density functional theory (DFT) calculations, we found that 2D nanosheets were superior to 1D nanotubes in terms of Na+ storage. Flexible NTO NSs enable efficient electronic/ionic conductivity while avoiding structural breakage. Whereas, ultra-long and rigid NTO NTs are prone to fracture and collapse during cycling, resulting in a sharp increase in resistance.
Figure 3. (a) CV curves of NTO NSs; (b) The contribution rate of capacitance and diffusion control capacitance of NTO NSs at different scan rates of 0.1~10 mV s-1; (c) CV curves of NTO NTs; (d) The contribution rate of NTO NTs capacitance and diffusion control capacitance at different scan rates of 0.1~10 mV s-1; (e) Nyquist plots (scatters) and fitted spectra (lines) of NTO NSs and NTO NTs using equivalent circuits (inset); (f) Simulated Rct and calculated DNa+.
(a,b) 片状和棒状NTO的原子模型,分别模拟NTO NSs和NTO NTs;(c,d) 计算得到的NTO NTs和NTO NSs应变-应力关系;(e)Na2Ti3O7(101) 和吸附Na+的Na2Ti3O7(101)的slab原子模型
【Article Link】
Deeper Insights into the Morphology Effect of Na2Ti3O7 Nanoarrays on Sodium-Ion Storage
https://onlinelibrary.wiley.com/doi/abs/10.1002/smll.202400845
【About the Corresponding Author】
Associate Professor Liu Jinlong Profile: He graduated from the Department of Applied Chemistry of Central South University in 2011 with a Ph.D. degree under the supervision of Professor Qiao Shizhang from the School of Chemical Engineering and Advanced Materials at the University of Adelaide, Australia, and then engaged in postdoctoral research at the University of Cambridge and the University of Auckland. He joined Central South University in 2021 and is currently a distinguished associate professor in the Department of Applied Chemistry in the School of Chemistry and Chemical Engineering. He has long been engaged in the design, synthesis and structural characterization of advanced energy materials and their application in new energy technologies such as batteries (lithium/sodium-ion batteries and metal-air batteries), supercapacitors, and electrocatalysis, as well as the design and screening of new chemical materials, electronic structure analysis and reaction mechanism exploration based on quantum chemical calculation and molecular dynamics simulation. It is currently in Angew. Chem. Int. Ed.、Adv. Mater.、Adv. Energy Mater.、Nano Energy、ACS Catal.、Chem. Eng. J.、Small、J. Mater. He has published more than 60 academic papers in internationally renowned journals such as Chem. A, 10 of which have been selected as ESI highly cited papers, with a total of more than 8,900 citations, and 4 national authorized invention patents.